This invention relates generally to improvements in devices and procedures for artificial joint replacement (arthroplasty). More specifically, this invention relates to an improved intramedullary bone plug for confining or restricting the placement of bone cement introduced under pressure into the medullary canal of a patient bone during arthroplasty surgery, such as a hip joint replacement.
Artificial or prosthetic joint structures are used extensively to repair or replace a patient joint, particularly such as hip, knee and shoulder joints. The prosthesis typically comprises a biocompatible structure or structures formed from cobalt-chrome alloy with a size and shape for secure affixation to a surgically resected patient bone. In many cases, the prosthetic device includes an elongated stem for slide-fit placement into the exposed medullary canal of a resected patient bone, such as the upper end of a patient's femur in the case of a hip replacement. A bone cement, typically methyl methacrylate, is often introduced under pressure into the medullary canal to provide a positive and stable prosthesis attachment to the patient bone. The pressurized bone cement is intended to fill the interstices of the bone structure in surrounding relation to the prosthetic device to result in optimal prosthesis fixation.
When pressurized bone cement is introduced into the medullary canal, it is necessary or desirable to use a restrictor or plug element to confine the cement to surrounding relation with the prosthesis, rather than to permit the bone cement to travel distally through the medullary canal in a direction away from the prosthesis. In this regard, numerous restrictor or plug devices have been developed for this purpose, and are adapted to be installed into the medullary canal immediately prior to placement of the prosthesis and bone cement. However, such prior restrictor or plug devices have not functioned in a fully satisfactory manner. To the contrary, such prior restrictor or plug devices have suffered from bypass leakage of the bone cement, or alternately from undesired sliding movement in a distal direction when subjected to bone cement under pressure. Either problem results in inadequate pressurization of the cement and corresponding less-than-optional fixation of the prosthesis.
There exists, therefore, a significant need for an improved bone plug for use in orthopedic surgery, wherein the bone plug is securely anchored within the medullary canal and further provides a high quality seal to prevent bypass leakage of cement. The present invention fulfills these needs and provides further related advantages.